The present invention relates to a vehicle seat assembly and in particular to a seat assembly that also carries a seat belt system and is configured to withstand the high seat belt loads incurred during a vehicle collision.
Vehicle seat belt systems are typically mounted directly to the vehicle structure. For example, most belt systems have the belt retractor mounted to the vehicle floor pan with the belt webbing extending upwardly along the B-pillar of the vehicle to a D-ring mounted to the pillar. The webbing then extends downward to a belt end connected to the vehicle floor adjacent to the retractor. A clasp is slidably movable between the end of the seat belt anchored to the vehicle floor and the D-ring on the B-pillar. A buckle is attached to the vehicle floor on the opposite side of the seat. When the clasp is pulled across the user and inserted into the buckle, the webbing forms a lap belt and a shoulder belt to retain the occupant in the seat assembly.
The position of the vehicle seat assembly in the vehicle is adjustable in at least the fore and aft direction. With adjustment, the seat assembly is moved relative to the seat belt attachment points such that it can become inconvenient and uncomfortable for a seat occupant to use the seat belt. For example, if the vehicle seat is moved to its forwardmost position, it may be difficult to reach back to grasp the seat belt clasp along the B-pillar. In addition, with the seat moved forward, the shoulder belt may rub across the occupant's neck creating a discomfort. If the seat is adjusted to its rearwardmost position, the shoulder belt may be located too far forward relative to the occupant such that the person's torso can move forward some distance unrestrained by the shoulder belt.
Accordingly, it is an object of the present invention to provide a three point seat belt system comprising a lap belt and a shoulder belt that is mounted to and carried by the seat assembly itself so that regardless of the position of the seat assembly in the vehicle, the belt system remains in a constant position relative to the seat assembly and seat occupant.
It is another object of the invention, of course, to provide a seat assembly capable of withstanding the seat belt loads incurred during a vehicle collision.
It is also an object of the invention to provide a seat assembly that is as structurally similar to current production seat assemblies to minimize nonstructural changes to the seat assembly.
It is a further object of the invention to include in the seat assembly of this invention features commonly found in seat assemblies such as a seat back recliner, a fore and aft seat adjuster, an adjustable lumbar support mechanism and a vertical lift mechanism to raise the seat cushion.
The seat assembly of the present invention includes a pair of fore and aft extending fixed rails disposed along the lateral sides of the seat assembly with each rail having a track portion adapted to engage with the track portion of a pair of slide rails mounted on each fixed rail. The slide rails include the previously mentioned track portion as well as a riser portion extending upwardly from the track portion. The seat cushion pan is coupled to the slide rails through a four bar linkage mechanism used to raise and lower the seat cushion.
The seat back frame is pivotally mounted to the slide rails and extends generally upwardly from the rear of the seat cushion in a conventional manner. The seat belt system includes a belt retractor attached to an upper slide rail along one side of the seat assembly near the rear of the seat assembly. The belt extends from the retractor upwardly through the seat back to the top of the seat back where the belt projects forwardly from the seat cushion and extends downwardly along the same side where the belt end is attached to the slide rail. A buckle assembly is attached to the slide rail on the opposite side of the seat assembly and a clasp is slidably carried by the belt webbing between the belt end and the upper end of the seat back. When the clasp is pulled over the user's body and inserted into the buckle, the belt webbing is drawn out of the retractor forming a shoulder strap and a lap belt.
To accommodate the seat belt loads applied to the seat back. The back frame is formed with a beam extending generally upwardly along the side of the seat back to which the belt retractor and belt end are attached. The beam has a tapered closed-section that compensates for the increasing moment along its length to provide uniform material stress. The beam is of a hollow structure which tapers in an upwardly direction so as to reduce the quantity of material used in the beam at the upper end where the moment carried by the beam is reduced.
The overall seat back frame structure is a quadrilateral with the upright beam forming one side of the quadrilateral. An upright member on the opposite seat side as well as upper and lower cross members are formed of a hollow tube, flattened in portions, and of significantly lesser structural capability than the upright beam. For lateral stability a diagonal brace (truss) extends from the upper end of the upright beam to the lower end of the opposite vertical frame member. The diagonal beam also has a flattened tubular structure.
The seat recliner mechanism is a single sided recliner on the same side of the seat as the seat belt assembly and is used to resist forward rotation of the seat back caused by seat belt loads applied to the seat back. The recliner mechanism includes a brace pivotally connected to the upright beam of the seat frame and extending downwardly and forwardly to a pivotal coupling with the upper slide rail. The forward end of the brace carries a nut through which a lead screw, rotatably carried by the sliding rail, is threaded whereby rotation of the lead screw moves the brace fore and aft along the slide rail to adjust the position of the seat back.
A seat back dump feature can be included in the seat assembly for use as the front seat in a two-door vehicle. The dump feature is made possible by providing the pivotal coupling of the brace to the seat back frame with a selectively releasable mechanism to enable the seat back to pivot forward to a dump position without readjustment of the seat back recliner mechanism being required.
A mechanical adjustable lumbar support mechanism is provided in the seat back and includes a support paddle carried by a single piece bent wire to move the paddle in and out relative to the seat cushion.
Further objects, features and advantages of the invention will become apparent from a consideration of the following description and the appended claims when taken in connection with the accompanying drawings.